Heat sink for a luminaire



FIG. 1 is a perspective view of the new design for a heat sink for a luminaire as seen from the bottom, right side;

FIG. 2 is a right side elevational view thereof, the left side being the same;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines illustrate portions of the heat sink for a luminaire and form no part of the claimed design. 

CLAIM The ornamental design for a heat sink for a luminaire, as shown and described. 